1. Field of the Invention
The present invention relates to a normally-open type clutch structure provided to a miniaturized vehicle.
2. Description of Background Art
A miniaturized vehicle is known which includes an oil pressure generating device and a clutch structure which automatically engages or disengages a clutch due to the generation of oil pressure. See, for example, JP-A-2003-329064.
This type of miniaturized vehicle includes an automatic speed-change mechanism and does not include a manipulator which manipulates the clutch (for example, a clutch lever) and the like.
However, in such a vehicle, the oil pressure generating device does not supply a clutch working oil when the vehicle is stopped and the engine is stopped. Thus, the supply of working oil due to an operation of a piston is not performed so that the clutch is always brought into an engaged state.
More specifically, in the conventional automatic speed-change mechanism, unless any separate manipulator which disengages a clutch is provided, the clutch cannot be disengaged so that the rotation is transmitted from a drive wheel to an engine whereby it is difficult, for example, for a rider to walk while pushing a motorcycle or the like.